Does the Second Amendment really protect assault weapons? Four courts have said no.

Almost exactly a year ago, a federal appeals court considered whether a Maryland law banning assault weapons was unconstitutional.

The law was passed in the aftermath of the Sandy Hook massacre, which left 20 first-graders and six adults dead after a man bearing an AR-15-style weapon stormed the school in Newtown, Conn.

“Nine terrified children ran from one of the classrooms when the gunman paused to reload, while two youngsters successfully hid in a restroom,” Judge Robert B. King of the U.S. Court of Appeals for the 4th Circuit wrote in the majority opinion. “Another child was the other classroom’s sole survivor. In all, the gunman fired at least 155 rounds of ammunition within five minutes, shooting each of his victims multiple times.”

The court ruled that the ban on assault weapons like the one Adam Lanza used at Sandy Hook — like the one that police say Nikolas Cruz confessed to using at Marjory Stoneman Douglas High School on Feb. 14 and that Omar Mateen used at Orlando’s Pulse Nightclub in June 2016 and Stephen Paddock used from the Mandalay Bay in Las Vegas on Oct. 1 — was constitutional.

It was not the first time a federal appeals court had ruled that a ban on assault weapons was permissible under the Second Amendment. It was the fourth time in the past decade. In fact, no federal appeals court has ever held that assault weapons are protected.

The question of assault weapons was not addressed by the Supreme Court when, in 2008, it held for the first time in District of Columbia v. Heller that the Second Amendment protects an individual right to possess a firearm. Justice Antonin Scalia, writing for the court, went out of his way to say that the right “is not unlimited.”

In each case that has reached a federal appeals court since then, bans on the semiautomatic guns known as assault weapons have been upheld, usually for the same two reasons.

Banning them, the courts have said, does not curtail the right of self-defense protected by the Constitution. There are plenty of other weapons — handguns and regular long guns — available to people to protect themselves.

At the same time, the courts have said, states and municipalities have legitimate reasons to ban AR-15-style weapons because of the dangers they pose, to schools, innocent bystanders and police.

That same argument is being made by advocates of an assault weapons ban in the wake of the killing of 17 people at Florida’s Marjory Stoneman Douglas High School.

Gun rights advocates, such as the National Rifle Association, have argued that such a ban would violate the Second Amendment.

As the NRA told the Supreme Court in 2015 as it unsuccessfully sought review of one of the four appeals court rulings: “Firearms that are commonly chosen by law-abiding citizens for lawful purposes cannot be banned. While some contours of the Second Amendment have been left to future evaluation,” it said in an amicus brief, “at least this much is clear from recent decisions by this Court.”

But that much has not been “clear” to the appeals courts that have reviewed the issue.

For the 4th Circuit judges in the Maryland case, the question came down to whether military-style weapons were necessary for self-defense and whether the government has a legitimate interest in regulating them.

King noted in the majority opinion that Maryland law enforcement officials could not identify a single case in which a Marylander had used a military-style rifle or shotgun, or needed to fire more than 10 rounds, to defend herself.

And although the gun groups had argued that assault weapons such as AR-15s were the most popular sporting rifles in the United States, the Maryland government argued that they also happened to be the most popular guns used in mass shootings.

Shooters used assault rifles in 21 percent of the massacres between 1982 and 2012, and used guns with large-capacity magazines in more than 50 percent of them, King said.

“Put simply,” King wrote, “we have no power to extend Second Amendment protection to the weapons of war that the Heller decision excluded from such coverage.”

The decision, predictably, angered gun-rights activists.

NRA spokeswoman Jennifer Baker said in a statement at the time, “It is absurd to hold that the most popular rifle in America is not a protected ‘arm’ under the Second Amendment.”

In another case (called Heller II), the Court of Appeals for the District of Columbia Circuit upheld a ban on assault weapons and large-capacity magazines in Washington. The appeals court said in an April 2011 decision that the ban did not impinge on the individual’s right of self-defense. Plus, the court said, the city had plenty of reason to believe that assault weapons were too dangerous in “self-defense situations.” With the ability to fire so many shots so rapidly, the judges said, such weapons pose “grave risks” to bystanders, not to mention police officers who might confront them on the streets.

Another appeals court considered the issue in April 2015, when the Chicago-based U.S. Court of Appeals for the 7th Circuit upheld by a 3 to 2 vote an ordinance in Highland Park, Ill., that prohibited possession of assault weapons, which the law defined as “any semiautomatic gun that can accept a large-capacity magazine.”

In this case as well, the court said the ordinance left residents “with many self-defense options,” such as handguns. Like the D.C. court, the 7th Circuit cited the dangerousness of assault weapons. “Why else are they weapons of choice in mass shootings?” the court said.

“A ban on assault weapons and large-capacity magazines might not prevent shootings in Highland Park … but it may reduce the carnage if a mass shooting occurs,” the court said.

Five months later, the U.S. Court of Appeals for the 2nd Circuit reached the same conclusion as it considered laws in New York and Connecticut that prohibited the possession of semiautomatic assault weapons and large capacity magazines.

It’s true, Judge Jose A. Cabranes wrote for a unanimous court, that the laws constituted an “outright” ban, “both broad and burdensome.”

However, the panel said, “semiautomatic assault weapons have been understood to pose unusual risks,” resulting in “more numerous wounds, more serious wounds, and more victims. These weapons are disproportionately used in crime, and particularly in criminal mass shootings like the attack in Newtown. They are also disproportionately used to kill law enforcement officers,” the court said.

The Supreme Court has declined to review any of these cases. A reason may be that at the moment there is no split among the appeals courts across the country, a factor that heavily influences the high court’s choice of cases. The appeals courts have all agreed that assault weapons bans are okay.

Meagan Flynn is a reporter on The Washington Post's Morning Mix team. She was previously a reporter at the Houston Chronicle and, prior to that, the Houston Press, where she covered criminal and social justice issues extensively.

Fred Barbash, the editor of Morning Mix, is a former National editor and London bureau chief for The Washington Post. He has also been an editor at Politico and Reuters, and was the managing editor of CQ Weekly magazine.